Valve, in particular a 4/2-way slide valve

ABSTRACT

The invention relates to a valve, in particular a 4/2-way slide valve ( 60 ), comprising a valve piston ( 67 ), which is guided in a longitudinally movable manner in a valve housing ( 25 ), for selectively connecting and disconnecting fluid connections in the valve housing ( 25 ), such as a pressure supply connection (P), a tank connection (T), and two utility connections (A, B), and comprising a magnetic system ( 49 ), to which current can be supplied, for controlling the valve piston ( 67 ), characterized in that, when no current is supplied to the magnetic system ( 49 ), the control pressure at one of the utility connections (A, B) can be set, in particular limited, by means of a control device ( 62, 70, 79, 80, 88 ) arranged in the valve housing.

The invention relates to a valve, in particular a 4/2-way slide valve,having a longitudinally movable, guided valve piston in a valve housingfor selectively connecting and disconnecting fluid ports in the valvehousing, such as a pressure supply port, a reservoir port and twoutility ports, and having an energizable magnetic system for actuatingthe valve piston.

Valves of this type are state of the art and are used in a wide varietyof systems for controlling fluid media. Document DE 42 27 767 A1 shows a4/2-way valve of the aforementioned type for controlling theregeneration system of a filter system for drinking water by way of anexample. In particular, 4/2 directional control valves are also used inhydraulic systems, for example for the supply of actuators, such asworking cylinders. If working cylinders controlled via directionalcontrol valves are used in working equipment, such as constructionmachinery, excavators, wheel loaders or the like, as actuators forlifting or gripping functions, particularly high demands are placed onthe operational reliability. A typical usage of working cylinders inconstruction machinery is, for example, a tool change for example bypicking up an excavator bucket, where a locking operation for coupling aworking arm to the excavator bucket has to be performed, wherein alock-out system is driven by a hydraulic cylinder for interlock with thetool in question. To avoid damage in the event that extending lockingbolts do not retract into the bolt holders in the event of incorrectpositioning, but collide with the tool to be picked up, it has to beensured that the locking bolts do not extend under the full pressure ofthe hydraulic system of the relevant machine, but at a working pressure,which does not damage the tool in the event of a collision, while therespective bolts are retracted at the normal system pressure. Thisentails a pressure reducing valve and a check valve forming a bypass tothe former installed downstream of the 4/2-way slide valve, resulting inincreased space requirements and cost for the safe control of theworking cylinder.

Based on this prior art, the invention addresses the problem ofproviding a valve enabling the reliable control of a working cylinderprovided for coupling processes at comparatively reduced effort andexpenditure.

According to the invention, this object is achieved by a valve havingthe features of claim 1 in its entirety.

According to the characterizing part of claim 1, a significant featureof the invention is that in the de-energized state of the magnet system,a control device arranged in the valve housing can be used to set, inparticular limit, the control pressure at one of the utility ports.Because in this way a valve unit fulfills both the travel control andthe pressure reducing function required for operational safety, thecontrol effort is reduced, both in terms of space requirements and interms of cost expenditure.

With particular advantage, the valve according to the invention isdesigned such that the control device passes the fluid pressure presentat one utility port on to a control pressure chamber for the purpose ofactuating a pressure-detecting piston in operative connection with thevalve piston, permitting traversing movements of the valve piston tocontrol the fluid flow between the pressure-supply port and this oneutility port against the action of an energy storage means, such as acompression spring.

In this case, the arrangement can be made with particular advantage suchthat the pressure-detecting piston passes in a movable manner through aguide stationarily arranged in the valve housing and one free end of itis in contact with the valve piston in any travel state of the pistonand the other end is in contact with an actuating rod of the magnetarmature of the magnet system. The valve thus forms a continuous coaxialunit from the magnetic system to the end of the valve housing. In thiscase, the control pressure chamber of variable volume may be encompassedby the valve housing and delimited by the guide and the valve piston.

To pressurize the pressure-detecting piston with the fluid pressurepresent at the one utility port, the control pressure chamber can bepermanently connected in a fluid-conducting manner to that utility portwhose fluid pressure is signaled to the control pressure chamber via adiaphragm or throttle and a recess in the valve piston.

For the control of the relevant, working cylinder to be supplied, thearrangement may advantageously be made such that in the energized stateof the magnet system, the valve piston assumes a position within thevalve housing, where the pressure in the pressure-supply port matchesthe pressure at the other user port, i.e. the working cylinder issubjected to the full system pressure in the energized state.

For an advantageous embodiment of the valve in the form of a valvecartridge adjoining the magnet system, the valve piston can be providedwith fluid guides on the outer periphery arranged concentrically to thepiston's travel axis, which depending on the position of the valvepiston permit at least one connection from the pressure-supply port tothe relevant utility port and from the relevant utility port to thereservoir port.

The energy storage means formed as a compression spring preferably actson that side of the armature facing away from the valve piston.

For the formation of the valve housing in the manner of a valvecartridge, the arrangement is preferably made such that the one utilityport to be controlled by the fluid flow for a de-energized magnet systementers the valve housing from the front and the other ports are guidedradially in the valve housing.

According to claim 20, the subject of the invention is also a fasteningdevice having at least one controllable hydraulic cylinder, whose pistonrod unit separates two working spaces from each other, which are eachconnected to a utility port of a valve according to one of claims 1 to19, wherein the fastening device is characterized in that the controldevice of the valve responds and outputs a mechanically adjustable,limited control pressure for actuating the piston-rod unit upon theextension of the piston-rod unit and its collision with a thirdcomponent, such as an excavator bucket.

Below the invention is explained in detail with reference to anembodiment shown in the drawing.

In the drawings:

FIG. 1 shows a schematic representation of the circuit of a valve devicehaving a 4/2-way slide valve according to the prior art for controllingthe working cylinder of a merely highly schematically indicatedfastening device;

FIG. 2 shows a schematic representation of the valve according to theinvention;

FIG. 3 shows a longitudinal section of an exemplary embodiment of thevalve according to the invention, inserted into a valve block, whereinan operating state corresponding to the energized magnet system isshown;

FIGS. 4 to 6 show representations of the exemplary embodiment in whichthe magnet system is shown in view and the valve housing is shown,without associated valve block, in a longitudinal section, illustratingdifferent operating states of the valve; and

FIG. 7 shows an enlarged and broken-off partial longitudinal section ofthe valve housing, wherein the operating state shown in FIG. 5 is shown

In FIG. 1 a valve assembly is denoted by 1, which valve assembly isprovided for actuating a working cylinder 3, which forms the actuatorfor a fastening device, of which only a bolt holder 5 is indicated in aschematically greatly simplified representation. The fastening device inthe present example is a so-called quick-coupler device used inconstruction machines such as excavators, wheel loaders 5 and the liketo install or disconnect a work tool such as a bucket in the course of atool change. In these devices, hydraulically extendable locking boltsengage with sleeves 7 in the bolt holder 5 for establishing a couplingconnection, wherein the locking bolts are formed directly by the pistonrod 9 of the respective working cylinder 3 itself or by a membermechanically connected to the piston rod 9. The relevant workingcylinder 3 is designed as a double-acting cylinder having a workingchamber at the rod side 11 and a working chamber at the piston side 13,of which the latter is connected to a utility port B and the workingchamber at the rod side 11 to a utility port A of the valve assembly 1.For the unlocking process, the working chamber at the rod side 11 can besupplied with pressurized fluid via the utility port A, and the workingchamber at the piston side 13 can be supplied with pressurized fluid forthe coupling process via the utility port B to extend the working piston15 and thus the piston rod 9 for the coupling engagement. The ports Pand T of the valve assembly 1 are connected to the hydraulic system ofthe associated construction machinery for this pressure supply, whereinthe system pressure of the hydraulic system is present at the port P andport T is connected to the reservoir.

The valve assembly 1 has an electromagnetically actuated 4/2-way slidevalve 17 for the optional connection of the pressure-supply port P andthe reservoir port T to the working chambers 11 and 13 of the workingcylinder 3. While the working space 11 for the retraction motion of thepiston 15 and thus the unlocking motion of the piston rod 9 and thelocking bolt is supplied with full system pressure, by switching the4/2-way slide valve 17 from the valve position shown in FIG. 1, theworking chamber at the piston side 13 has to be supplied with reducedoperating pressure for the extension of the piston 15 and thus therespective locking bolt to avoid mechanical damage to the respectivelocking bolt and/or the bolt holder 5 in the event of a collision. Thevalve assembly 1 therefore has a pressure-reducing valve 21 between the4/2-way slide valve 17 and the working chamber at the side of the piston13, which pressure-reducing valve is set to a pressure producing areduced piston force, which is harmless in the event of a collision. Toallow the volume displaced from the working chamber at the side of thepiston 13 to flow to the reservoir substantially without pressure whilethe piston 15 retracts, a bypass of the pressure-reducing valve 21 isrequired, which is formed by an additional check valve 23.

The valve 60 according to the invention, the schematic representation ofwhich is shown in FIG. 2, comprises the overall functions of the valveassembly 1, i.e. both the switching function of the 4/2-way slide valve17 and the pressure-reducing function of the pressure reducing valve 21,wherein the additional check valve 23 of the valve assembly 1 is alsoomitted. The more detailed design details of the valve according to theinvention 60 are shown in the FIGS. 3 to 7 below.

As shown, the exemplary embodiment has a valve housing 25, which can beinstalled in the manner of a valve cartridge in a valve block 27, whichis shown only in FIG. 3, and has the connection points 29 and 31 for theutility ports A and B and the connection points 33 and 35 for thepressure-supply port P or the reservoir port T. As most clearly shown inFIGS. 4 to 7, the outer periphery of the valve housing 25 is stepped, sothat, starting from the end of the bottom in the figures, sectionshaving a reduced diameter 37, 39 and 41 are formed, which are sealedagainst the valve block 27 by the sealing means 43, 45 and 47 located atthe non-recessed peripheral sections. For installation in the valveblock 27, the valve housing 25 has, at the end facing towards a magnetsystem 49 provided for actuation, an external thread 51, to which ascrew-in body 53 can be screwed, which has the form of a hollow screwwith an external hexagon 55 and which has an external thread 57 on theside facing away from the magnet system 49, which external thread isused to screw it into the valve block 27, wherein a sealing ring 59forms the seal at a step of the screw 53. On the side facing the magnetsystem 49, the screw-in body 53 has an internal thread 61, into whichthe end section 63 of the pole tube 64 (FIG. 3) of the magnet system 49is screwed, wherein a sealing ring 52 forms the seal.

The valve housing 25 has a circular cylindrical piston guide 66 for avalve piston 67 on the inside. In the state shown in the figures, inwhich the screw-in body 53 is used to screw the valve housing 25 to thepole tube 64 of the magnet system, a guide body 69 is mounted betweenthe end 68 of the valve housing 25 and the end section 63 of the poletube 64, which guide body forms a coaxial passage as displacement guidefor a pressure-detecting piston 70, the end of which facing the magnetsystem 49 abuts the end of an actuating rod 71 of the armature 72 (FIG.3).

The armature 72, the actuating rod 71 and the pressure-detecting piston70 are pre-tensioned for motion in the direction of the valve piston 67by means of a compression spring 73, which is supported on the one handby the armature 72 on the side facing away from the actuating rod 71 andon the other hand by the pole core 74 (FIG. 3) of the magnet system 49.A contact spring 76 is used to keep the piston end 75 of the valvepiston facing the pressure-detecting piston 70 permanently in contactwith the pressure-detecting piston 70. It rests against a collar 77formed at the free end of the valve housing, which collar delimits acentral, end opening of the valve housing 25 and forms the utility portB there, which, as shown in FIG. 3, is connected to the connection point31. The valve piston 67 has a coaxial inner cavity 78, which extendsfrom the open end of the utility port B to just before the piston end 75abutting the pressure-detecting piston 70 where the valve piston 67 isclosed except for a passage having a restriction 79. This restriction 79connects the utility port B to a control pressure chamber 80, which isformed between the piston end 75 and the guide body 69. As a result, thefluid pressure of the control pressure chamber 80 is effective at thecontrol pressure chamber 80 facing the piston surface 62 of thepressure-detecting piston 70.

The valve piston 67 is provided, in the manner usual for-way slidevalves, on the outer periphery having direction fluid guides 81 and 82extending concentrically to the axis of travel in the axial direction,which can be used, depending on the control position of the valve piston67, to establish connections between the pressure-supply port P andutility port A or B and between the reservoir port T and the utilityport A or B. For these connections, openings 83 for the pressure-supplyport P, openings 84 for the reservoir port T and openings 85 for theutility port A are formed in the wall of the valve housing 25; these areonly numbered in FIG. 7. As can also best be seen in FIG. 7, thenon-recessed peripheral sections of the valve piston 67, which delimitthe fluid guides 81 and 82, form control edges which control the fluidpassage at the openings 83, 84 and 85. The control edge 88 is present atthe drilled hole 83, which leads to the pressure-supply port P. Thecontrol edge 89 is disposed at the edge of the drilled hole 84, whichleads to the reservoir port T. The edges 90 and 91 at the edge of thenon-recessed area 92 control the passage at the openings 85 of theutility port A.

FIGS. 3 and 6 show an operating state in which the magnet system 49designed as a so-called “pulling magnet” is energized by supplying itswinding 93. In the armature chamber 94, which is vented to theenvironment in the usual manner via the passages 95 and 96 in thearmature 72 or in the pole core 74, the armature 72 has moved againstthe action of the compression spring 73. As the piston end 75 of thevalve piston 67 abuts against the piston surface 62 of thepressure-detecting piston 70 under the action of the contact spring 76,it has moved upwards in the figures into the position shown in FIGS. 3and 6 in conjunction with the actuating rod 71 of the armature 72. Inthis position, the control pressure chamber 80 has the smallest volumecorresponding to the size of a gap that is formed by an annular rib 97between the end 75 of the valve piston 67 and the guide body 69 whichrib protrudes from the guide body 69 coaxially to the pressure-detectingpiston 70. This position of the valve piston 67 assumed when the magnetsystem 49 is energized, causes unlocking, as the openings 83 of thepressure-supply port P at the valve housing 25 are connected to theopening 85 of the pressure-supply port A via the fluid guide 81, whilesimultaneously the utility port B is connected to the openings 84 of thereservoir port T via the drilled holes 87 such that the volume displacedfrom the working chamber 13 of the working cylinder 3 during theunlocking process flows to the reservoir.

The energization of the winding 93 is interrupted for a lockingoperation. For this purpose, the compression spring 73 displaces thearmature 72 and via its actuating rod 71 the pressure-detecting piston70 to the position shown in FIG. 4, wherein the valve piston 67 thusdisplaced now connects the openings 83 of the pressure supply port P atthe valve housing 25 to the utility port B via the drilled holes 86 inthe valve piston 67, while the openings 85 of the utility port A areconnected to the openings 84 of the reservoir port T via the fluid guide82, such that the working piston 15 moves to extend the piston rod 9 andthe volume from the working chamber 11 of the working cylinder isdisplaced towards the reservoir T. Simultaneously, the pressure in thecavity 78 of the valve piston 76 of the utility port B starts acting inthe control pressure chamber 80 via the passage having the restriction79 and pressurizes the effective piston surface 62 of thepressure-detecting piston 70. At a pressure level that can be setmechanically by the design of the compression spring 73 and the contactspring 76 and adjusted by the size of the effective piston surface 62 ofthe pressure-detecting piston 70, the pressure-detecting piston 70 movesagainst the force of the compression spring 73. The valve piston 67,which follows this movement due to the action of the application spring76, is moved from the position shown in FIG. 4 to a control positioncorresponding to the balance of the spring forces and the piston forceof the pressure-detecting piston 70, cf. FIGS. 5 and 7, in which controlposition the position of the control edge 88 of the valve piston 67 atthe openings 86 of the pressure-supply port P controls the pressureeffecting the extension movement of the piston 15 at the utility port Bto a desired safe value. The valve 60 according to the invention in thatway fulfills not only the switching functions for the unlocking andlocking operations by energizing and de-energizing the winding 93 of themagnet system 49, but also fulfills a pressure control function,eliminating the pressure-reducing valve 21 with the check valve 23provided in the prior art.

1. A valve, in particular a 4/2-way-way slide valve (60), having alongitudinally movable, guided valve piston (67) in a valve housing (25)for selectively connecting and disconnecting fluid ports in the valvehousing (25), such as a pressure-supply port (P), a reservoir port (T)and two utility ports (A, B) and having an energizable magnet system(49) for actuating the valve piston (67), characterized in that in thede-energized state of the magnet system (49) a control device (62, 70,79, 80, 88) arranged in the valve housing can be used to set, inparticular limit, the control pressure at one of the utility ports (A,B).
 2. The valve according to claim 1, characterized in that the controldevice passes the fluid pressure present on one utility port (B) on to acontrol pressure chamber (80) for the purpose of actuating apressure-detecting piston (62, 70), in operative connection with thevalve piston (67), permitting traversing movements of the valve piston(67) to control the fluid flow between the pressure-supply port (P) andthis one utility port (B) against the action of an energy storage means,such as a compression spring (73).
 3. The valve according to claim 1,characterized in that the pressure-detecting piston (62, 70) passes in amovable manner through a guide (69) stationarily arranged in the valvehousing (25) and one free end (62) of it is in contact with the pistonin any travel state of the valve piston (67) and the other end is incontact with an actuating rod (71) of the magnet armature (72) of themagnet system (49).
 4. The valve according to claim 1, characterized inthat the control pressure chamber (80) of variable volume is encompassedby the valve housing (25) and delimited by the guide (69) and the valvepiston (67).
 5. The valve according to claim 1, characterized in thatthe control pressure chamber (80) is permanently connected in afluid-conducting manner via a diaphragm or throttle (79) and a recess(78) in the valve piston (67) to that utility port (B) whose fluidpressure is signaled to the control pressure chamber (80).
 6. The valveaccording to claim 1, characterized in that in energized state of themagnet system (49), the valve piston (67) assumes a position within thevalve housing (25), where the pressure in the pressure-supply port (P)matches the pressure at the other user port (A).
 7. The valve accordingto claim 1, characterized in that the valve piston (67) provided withfluid guides (81, 82) on the outer periphery arranged concentrically tothe piston's travel axis, which depending on the control position of thevalve piston permit at least one connection from the pressure-supplyport (P) to the relevant utility port (A, B) and from the relevantutility port (A, B) to the reservoir port (T).
 8. The valve according toclaim 1, characterized in that the energy storage means, in particularin the form of the compression spring (73), acts on that side of thearmature (72) facing away from the valve piston (67).
 9. The valveaccording to claim 1, characterized in that the one utility port (B) tobe controlled by the fluid flow in de-energized magnet system (49)enters the valve housing (25) from the front and the other ports (A, P,T) are guided radially in the valve housing (25).
 10. The valveaccording to claim 1, characterized in that the relevant fluid guide(81, 82) is formed from at least one groove-shaped recess in the valvepiston (67).
 11. The valve according to claim 1, characterized in thatthe two fluid guides (81, 82) in the valve piston (67) are separatedfrom each other by a non-recessed section (92) thereof, which hasopposing edges (90 and 91) in the direction of the relevant fluid guide(81, 82), each of which control the passage at at least one opening (85)in the valve housing (25) of the utility port (A) for one (81) or theother fluid guide (82).
 12. The valve according to claim 1,characterized in that the two fluid guides (81, 82) transit on theiropposite sides in further non-recessed areas of the valve piston (67),each having at least one drilled hole (86, 87) whose edge forms at leastpartially in conjunction with an assignable opening (83 or 84) a controledge (88 or 89) in the valve housing (25) for the pressure supply port(P) or for the reservoir port (T).
 13. The valve according to claim 1,characterized in that in every control position of the one non-recessedsection (92) of the valve piston (67), the one fluid guide (81) has apermanent fluid connection with at least one further opening (83) forthe pressure-supply port (P) disposed in the valve housing (25), whichis axially spaced from the at least one opening (83) for the same port(P) in the valve housing (25) and that on the inside of the valvehousing (25) the two axially spaced openings (83) are separated fromeach other by a web-like non-recessed section of the valve piston (67)in any of its travel positions.
 14. The valve according to claim 1,characterized in that in every control position of the one non-recessedsection (92) of the valve piston (67), the other fluid guide (82) has anat least partial permanent fluid connection with at least one furtheropening (84) for the reservoir port (T) disposed in the valve housing(25), which is axially spaced from the at least one opening (84) for thesame port (T) in the valve housing (25) and that on the inside of thevalve housing (25) the two axially spaced openings (84) are separatedfrom each other by a web-like non-recessed section of the valve piston(67) in any of its travel positions.
 15. The valve according to claim 1,characterized in that viewed in the direction of travel of the valvepiston (67), the axial length of a groove-like fluid connection (81) isselected smaller than that of the other groove-like fluid connection(82).
 16. The valve according to claim 1, characterized in that therelevant groove-like depression of the two fluid connections (81, 82)seen on the bottom are located in a common plane parallel to therespective displacement direction of the valve piston (67) and that thegroove-like depressions continuously encompass the valve piston (67) onthe outer periphery.
 17. The valve according to claims claim 1,characterized in that all the non-recessed areas of the valve piston(67) are located in a common plane, which runs parallel to the bottomsides of the fluid connections (81, 82).
 18. The valve according toclaim 1, characterized in that the respective openings (83, 84) for thepressure-supply port (P) or for the reservoir port (T) form pairs ofstacked rows of openings in the valve housing (25).
 19. The valveaccording to claim 1, characterized in that in the valve piston (67) aplurality of drilled holes (86, 87) each form a separate row of drilledholes, which abut at least in a displacement position of the valvepiston (67) between the assignable pairs of rows of openings (83, 84) inthe direction of the valve housing (25) and opening onto its inner wall.20. A fastening device having at least one controllable hydrauliccylinder (3), whose piston-rod unit (9, 15) separates two workingchambers (11, 13) from each other, which are both connected to a utilityport (A, B) of a valve (60) according to claim 1, characterized in thatduring the extension of the piston-rod unit (9, 15) and its collisionwith a third component, such as a bucket (5), the control device (62,70, 79, 80, 88) of the valve (60) responds and outputs a mechanicallyadjustable, limited control pressure for actuating the piston-rod unit(9, 15).